Catecholamines produce complex changes in aqueous humor dynamics and intraocular pressure (IOP). The usual ocular effect of beta-adrenergic receptor stimulants is to lower IOP although occasionally a rise in IOP occurs. The objective of this project is to examine the role of beta-adrenergic receptors in altering fluid dynamics in the eye of the rabbit and to correlate these effects with biochemical changes. This will be accomplished by studying and comparing the ocular effects of isoproterenol and epinephrine with those of more selective beta-adrenergic drugs in three types of experiments: Study A: To evaluate the dose-response activities of selective beta-adrenergic drugs on normotensive and hypertensive eyes. Study B: To elucidate the mode by which beta-adrenergic drugs alter aqueous humor dynamics and IOP. Study C: To determine changes in the levels of intracellular messengers (cyclic nucleotides and prostaglandins) in the aqueous humor during the action of beta-adrenergic agonists in the absence and presence of selective beta-adrenergic receptor antagonists. In summary, this research project should clarify the role of beta-adrenergic receptors in controlling the physiology of aqueous humor and provide a rational basis for the use of selective beta-adrenergic drugs in controlling eye diseases, such as glaucoma.